Knee lock for artificial legs



Dec. 1, 1931. J, JEP$QN 1,834,491

KNEE LOCK FOR ARTIFICIAL'LEGS Filed Aug. 22, 1929 tion.

Patented Dec. 1, 1931 NITED JOHN H. JEPsoN, or, MINNEAPOLIS, MINNESOTA Iwas oci: r Artrrrrcmn L tes Application filed August 22, 1929. 's riain387,679;

My present invention has for its object the provision of a simple andhighly eflicient manually controlled knee lock for an artificial leg,for a disartic'ulation at the hip, or foran amputation abovethe kneethat leaves the stump so short that the patient'cannot control. themovement of-the artificial leg with which he is fitted and particularlywhen he is learning to walk or when going down stairs. By the use ofthis knee lock, the lower leg section maybe lockedatwill to the upperleg section'ofthe artificial-leg,

thus causing the'pati'ent to walk stiff legged,

but at the same time it gives himcontrol over the -moveme'nt of theartificial leg,

To the above end, the 'invention'consists of the novel devices andcombination of devices hereinafter described and defined in the claims.1

In the accompanying drawings, "which illustrate the invention," likecharacters indicate like parts throughout the several views.

Referringto the drawings Fig. 1 is a fragmentary view in front/elevation'showing an artificial leg at the knee joint for an amputationabove-the'knee and having the inventionembodied therein;

Fig. 2 is aview partly in side-elevation and partly in'section taken onthe line 2-2 of Fig.1;

Fig. 3 is a fragmentarydetail view with some parts sectional on theirregular line 33 of Fig. 1 on an enlarged scale; I

Fig. 4 is' a perspective View ofthe anchor plate, on an enlarged s'cale,removed from the upper leg sectiomand with the knee lock removedtherefrom; T V i S Fig. 5 is a fragmentary perspective view of the lockplate, onan enlarged scale, and

removed from the lower leg section; and

Fig. 6 is a fragmentary detail view-with some parts sectioned on theline 6-6 of Fig. 2, on an enlarged scale. i

The numerals 78 ndicate the upper and lower sections of an artificialleg, fo r an am- "p'utation above tlieknee, connected by a knee 'joint9which sectionjand knee joint may be of j standard or any fwellg-kinownconstrucclearance for the detent l6.

.Al'simplecontrol is provided for the main thereof.

The knee lock includes avertically dis posed main-lever 10intermediatelyfulcrumed at llto-a pair ofilaterally spaced rearwardlyprojecting bearing flanges on an anchor plate lb and between whichflanges said lever extends and is held thereby against lateral shiftingmovement. This anchor plate 13 is fitted to the inner'sur face of theupper legsection 7 and rigidly'secured by nut equipped bolts 15 tosaidsection.

:Theknee lock,as shown, is at the .front and transverse center oftheartificial' leg and the V fulcrum 1 1 is substantially at the sameelev'ation as the axiszof the knee oint 9. Formed on thelower end'of.the lever 10 is 'a wide forwardly projecting-hook or detent-16-whichworks'through an aperture'17' in the upper legv section. 7 forcooperation with a lock plate 18. This lockplate 18 is fitted to theinner surface of the lower leg sections,- rigidly secured theretoYbyrivets 19 .or other fastening devices, and is pro vided near. its topwith an aperture 20 into which the detent l6 projects'when in operativeposition for engagement with the lock 5 plate above said aperture toconnect the two 7 leg sections and 8, thereby holding the sameistittwhen straight. The lower leg section 8 atitheaperture 20 isrecessed at 21 to aflord 8'0 lever -10,. operable from the exterior ofthe legto movethedetent 16 into. orout. ofin- -terlocking engagementwith the'lock plate 18. :This control is in the 'formzof a shortwidelever 22in bell-crank arrangement with main -lever10. and-its'inner armisbifurcated. to .receive, between its prongs, the transversely reducedinner arm of the mainlever' 10, which works therebetween and is attachedthereto 5 by. a cam connection. -Said cam connection,

' as shown, comprises a longitudinally extended slot 24 in the inner armof the main lever 10, and acam pin 25, which extends through .saidslotand is anchored to the prongs of' 5 the? secondary lever 22. The outerarm of the secondary lever 22 works in an aperture 26, in the: upper legsection 7 atthe front A latch 27 and cooperating stop lug 28 nylonprovided for holding the secondary lever 22 with a detent 16 in eitheran operative or an inoperative position. This latch 27 in is the form ofa fiat member, which extends transvcrsely of the secondary lever 22, ismounted in a channel-like seat 29 formed therein and intermediatelypivoted at 30 to said lever. A coiled spring 31 mounted in spring seatsin the long arm of the secondary lever 22 and latch 27 yieldingly holdssaid latch in an operative position. The stop lug- 28 is formed with theanchor plate 14, extends in the path of movement of the'sh'ort end ofthe latch 27 and holds the secondarywlever=22 with the detent 16 ineither an operative or an inoperative position.

a When the :latch27 isabovethezstop lug28, the detent 16 is in anoperative position in :which it interlocks with the .lock .plate 1 8,and-holds :the :legsections 7 and 8 stiff and when said latch is belowsaid lug, it holds the detent :16 in an inoperative position, asindicated by broken lines in Fig. :2. This ilatch'27 extends slightlyoutward of the outer .face of the upper leg sections 7 where the samemay be easily manipulated by the .pa tient through his clothing torelease said latchfrom'the stop lug28 by a lifting movement thereof,into a position,in"-wl1ich it will .pass over'ithe stop lug 28 duringthe move- -ment ofthe secondary lever 22. Said latch :27 also affords aconvenient finger piece on dihevsecOlldaly lever :22 by which .it may bemanipulated -:to operate the main lever 10, hence the detent 16.

For the purpose of this .case .itzis :not thought :necessaryi'toillustrate the kneelcon- :trol except the flexible connection 32 betweentheleg section 7-8 atthebackthereof which has a slight longitudinalstretch, limits the forward swinging movement of the lower leg=sectionr8in respect .-to the upperleg sec tion 7 :and stops the same whenproperly aligned with said :upper leg section. This connection 32 maybeof. any well-knownlcon- =struction. The relation between .the detent16 and lock plate 18 is suehthat thenonnection '32 must be placed underslight tension by:a backward bending of thexleg atithekne'e -j oint itocause the lock detent 16 :to enter the aperture 20 in the lock plate 18.iThisitenslon' under which themember 32zis placedrseicurely'holdsthezdetent 16 interlocked with "the' latch late 18 so that thereiisnoilost moition' tliere etween.

From the above description, it visievident that :the above describedknee lock maybe easilyoperated by the patient through his clothing .to:render said lock either -'operative or inoperative at will.rFurthermore,.theiknee lock is substantially entirely encased within theleg so that-it doesnot have any protruding parts that wouldholdthatpatientas clothing away from the leg and thus beaconspicuous.

l/Vhat I claim is:

1. The combination with the upper and lower sections of an artificialleg, and a knee joint connecting the same, of a lock for the knee jointwithin said leg for holding the sections thereof stifi when in apredetermined position, said lock comprising a main lever pivotedin'termediateof its ends to :the upper leg sect-ion and a secondarylever pivoted intermediate of its ends to the upper leg section,=saidtwo leversfloei ng at an angle to each other, a positive cam connectionbetween the inner-arms of-said two levers, said main lever having adetent on its outer arm, the outer armof the secondary lever beingarranged where the same may be manually operated from theexterior ofsaid'leg, alock ,plate on .the lower-leg sectionarranged to be engagedby the detent for holding the leg section stiff when in apredeterminedposition, a movable latch :memberron the outerarm of thesecondary lever, and .a cooperating stop lug on the upper leg sectionfor positively holding :the secondary lever with the main lever in aposition inavhich its detent is interlocked with the lock plate. y

2. The combination with the upper and lower sectionsof an artificialleg, anda knee joint connecting the same, of a lock for -:the knee jointwithin said leg vfor holding the sections thereof stiffwhen-inapredetermined iposition, vsaidqloc'k comprising a main leverpivoted intermediate of its ends to the upper leg section and asecondary lever pivoted lin- =termedi-ate of .its ends to the upper-legsecition,:said,two levers bpeing=at anangletoeach other, a positive cam"connection between the inner arms of said two levers, said main leverhaving a detention its outer arm, the outer arm If the secondary {leverbeing arranged where the same ;may be manually operatedaf-rom-ltheexterior' oflsaid leg,a lock plate on the 'lower'leg sectionarranged to be engaged by the detent for holdinwthe leg, section stiffwhen :in a predetermined ;position, a movable latch member on the outerarm of the secondary lever, :and a cooperating stop lug on athe upperleg section for positively (holding the secondary lever'withthe mainlever-in a :position in which its detent is either :interlocked withztheilock plate or Lreleased .there from. a

3. The combination with the upper and lower sections :of'anartificialleg, and a knee joint connecting the same, of a lock for the knee jointwithin the :leg: for 'holdingthe sections .thereof still when in apredetermined :position, said lock comprisinga main lever and asecondary lever, ieachaof .whichis :piV- .oted :intermetlia'te (if its:ends-to rthe upper leg section, and a lock shoulder on tthe :lower ileg;section,-said1 two leversibeing substantialzly perpendicular to eachother and in the same .;.plane with their inner armsrldirectly connectedfor compound pivotal and sliding movements, the one upon the other, saidmain lever having a detent on its outer'end constructed and arranged tointerlock with the lock shoulder, the outer arm of the secondary leverbeing arranged whereby the same may be manually operated from theexterior of the leg.

In testimony whereof I aflix my signature.

JOHN H. JEPSON.

